Is my Molly pregnant?

Question
QUESTION: Hi
I have a silver molly and a orange molly. I'm pretty sure they are male and female. I know Mollies are easy to breed and I was wondering if my female is pregnant. She is bigger then my male and I've seen my male chasing her. She is round and I can basically see right through her. The stomach looks black and  kind of strange for a normal stomach. Thats basicly all I know. I was thinking of putting some guppies in my tank too. I only have two fish in my tank now. Will they be fine together? Would they
cross-breed?

ANSWER: Emma,
It is very possible that she is pregnant. The females are larger than the males so her being bigger could just be nature. Females also have a gravid spot, which is black, and back by the anal fin. It becomes more noticeable when they are pregnant. Mollies are brackish water fish. This means they need to have some salt in their water. Guppies are also brackish so they usually do very well together. Just do not add too many fish to the tank because you do not want to over stock the aquarium.

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QUESTION: Hi Jaymie,
Your answer really helped! I forgot to add she is VERY active!
Anyway I'm going to PetSmart tonight and I'm probably going to get some guppies. I did have guppies before but they died because my brother forgot to put the de-clor in. Is it because of that or were they not hardy? Is there a chance if I get male and female they won't eat their babies? And any thing on guppies would be great!
Thanks for your help,
Emma

Answer
Emma,
It is very important to add the water conditioner with all fish. The chlorine in the tap water can and usually does kill them. Unless the tank is heavily planted, guppies will eat their own babies as will the mollies.

http://guppyz.tripod.com/guppy_care.html